In an example scenario, a system can use a single interface for both data communications and power. For example, some single wire systems have two pins, one for the single wire interface and one for ground. Some single wire systems are driven by a fixed value pull-up resistor. There, the system power is limited by design to be within the limits of the specified resistor value. The system design can be matched to this value.
Additionally, in one example scenario, various chips are configured to operate at lower voltages, and the current demands may exceed the amount of current that may be supplied with a simple resistor. To meet those demands, some systems may be designed to operate in two modes: input/output (I/O) mode and execution mode. During I/O mode, the resistor would power the system. During execution mode, the user would provide an alternate power source, typically an output from another chip, to provide extra drive.
However, in an example scenario, two-mode systems can have disadvantages compared to simpler systems. For example, a two-mode system may implement timing control from the user, where the user must know when to turn on the alternate source, and when to turn it off to allow I/O. As another example, the two-mode systems may be designed to handle the execution mode current through the alternate source. The alternate source may be designed to meet certain design tolerances to meet multiple maximum requirements of the chip, e.g., timing and power requirements.